Product sterilizing apparatus and method



Aug. 19, 1952 w. M K. MARTIN PRODUCT STERILIZING APPARATUS AND METHOD 3 Sheets-Sheet 1 Filed May 17, 1948 JNVENTOR. WILL/AM McK. MART/N ATTORNEY Aug. 19, 1952 w. MCK. MARTIN PRODUCT STERILIZING APPARATUS AND METHOD 3 sheets-sheet 2 Filed May 17, 1948 w M f A 6 M a m 6 n MM 4 5 4 M Y :J 4 B IN V EN TOR.

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Patented Aug. 19, 1952 UNITED PRODUCT STERILIZING APPARATUSI AND METHOD William McK. Martin, San Mateo, Calif., assignor to James Dole Engineering 00., a corporation of Nevada Application May 17, 1948, Serial No. 27,523

9 Claims. '1

My invention relates to the sterilization of products, especially food products, and more particularly to an improved apparatus and method for sterilizing such products by cooking them in sealed containers in which the products have been previously packed.

'In a popular type of commercial apparatus for the sterilization of food products, containers such as tin cans or glass in which the product is {packed and which are subsequently sealed, are

introduced into a so-called continuous type pressure cooker for effecting the sterilization. With most products, it is necessary to sterilize the same at a temperature above 212 F., the specific temperature and time required for steriliaztion being determined by the particular type of product being processed as is well known in the art. Steam is employed as a heating medium; and it is necessary to maintain the steam in the cooker above atmospheric pressure in order to obtain the required temperature about 212 F. Hence, in such continuous type cookers, special inlet and discharge valve means has to be employed with the cooker to permit the entrance and exit of the product filled containers, while at the same time maintaining the super-atmospheric pressure. This renders the apparatus more or less cumbersome and relatively expen- SlV6..

My invention is designed to obviate the necessity of special valve means in a continuous cooker of the type described, for maintaining the heating steam therein above atmospheric pressure. It has as its objects, among others, the provision of an improved apparatus and method for eifecting sterilization of a product at substantially atmospheric pressure, thus eliminating the valve means previously pointed out; in which improved means is provided for effecting efiicient agitation of the containers and their contents, so as to cause rapid and efficient heat penetration through the product to effect eflicient sterilization; and which are relatively simple, inexpensive and easy to operate. Other objects of my invention will become apparent from a perusal of the following description thereof.

In general, I accomplish sterilization of the product at atmospheric pressure by introducing the sealed product filled containers into a sterilizing zone or chamber having valveless inlet and discharge openings, and into which steam is introduced for heating purposes. Outside heating means is applied'to the steam to superheat the steam at a temperature above 202 F. at substantially atmospheric pressure, thus providing an adequate sterilizing temperature in the apparatus. Preferably, the sterilizing chamber is employed in conjunction with a temperature holding chamber in which the sterilizing temperature is maintained, and which communicates with a cooling chamber wherein the sterilized product is cooled according to well known practice.

In order to effect thorough penetration of heat through the product as it is conducted through the sterilizing chamber in the sealed containers, I employ improved container agitating mechanism in the sterilizing chamber, and also preferably in the cooling chamber to enhance cooling. Such agitating mechanism comprises broadly a supporting member for the containers along which the containers are moved in one general direction by suitable means while they are supported on their sides. As the containers are thus moved, the supporting member therefor is given a rapid back and forth reciprocating motion, and this imparts a rapid back and forth rolling motion to the containers, thus thoroughly agitating them and their contents. Although the agitating mechanism described is of particular applicability in my improved sterilizing apparatus and method, it may be used anywhere in product processing when it is desirable to agitate the contents in the containers.

Reference is now made to the drawings for a more detailed description of a preferred embodiment of my invention, in which:

Fig. '1 is a more or less schematic longitudinal section through the apparatus of my invention, with a portion broken away to shorten the view;

Fig. 2 is an enlarged fragmentary longitudinal section through the conveying and agitating mechanism; portions being broken away to shorten the View;

Fig. 3 is a fragmentary transverse vertical section taken in a plane indicated by line 33 in Fig. 1;

Fig. 4-. is an enlarged fragmentary transverse vertical section taken in a plane indicated by line 4-4 in Fig. 1; and

Fig. 5 is an enlarged fragmentary transverse vertical section taken in plane indicated by line 5-5 in Fig. 1.

With referense to Fig. l, the apparatus com prises elongated housing structure 2 of any suitable material such as metal 3 supported on suitable supporting standards 6. One end of the housing structure includes a sterilizing zone or chamber 1 having a valveless inlet opening}! in of the conveyor reaches.

its end for containers 9 which are introduced into the chamber by means of a conventional chute conveyor H. Steriliz-ing chamber 1 communicates with an intermediate temperature holdin zone or chamber [2 segregated from the sterilizing chamber by partition wall l'3 having valveless openings i4 gfor passage of the reaches of an endless conveyor 16 to be subsequently described in greater detail. Preferably, opening l4 through which the upper reach of the conveyor passes is provided with a flex ble .closed flap L5 secured to partition wall [3 to permit passageof various size cans While at the same time preventing escape of excessive quantities .of steam which is introduced into chamber .1.

At the end opposite to the sterilizing chamber end, housing structure 2 is provided with a cooling zone or chamber I! having at its end a valveless discharge opening l8 from which the con tainers discharged fromthe apparatus are conducted by a conventional chute conveyor 19. Cooling chamber 1:! is segregated from intermediateitemperature holding chamber 12 by partition wall 12-1! having valveless openings 24 for passage Preferably, th inside of sterilizing chamber "i and temperature holding chamber 42 are lined with suitable moisture resistant insulating material 22, such as corrosion-resistant sheet metal backed by glass wool or other suitable insulating material.

' Endless conveyor t6 extends all the way through housing structure 2 from the inlet end of sterilizing chamber 7 to the discharge end of cooling chamber I1, and comprises spaced endless chains 23 turning about sprockets 24 secured to shafts 25, one of which is driv n by a spro chain drive 27 .as is indicated in Fig. l.- Chains 23'are joined'together by transversely extending bars :28' spaced apart a distance greater than the width of the lar est containers adapted to be handled by the apparatus; and as can be seen more clearly from Figs. 4 and 5, longitudinally extending stationary guide bars 29 spaced apart al l' tane reaterthan the len th of such l-arsestcontaine'rs, are provided to guide the containers in adjacent lines or rows through the apparatus as they are conducted in one general direction therethrough by the cross bars 28 of the endles conveyor. For supporting containers 9 as they are conducted by the endless conveyor, stationary supports .31 are provided at the turns of the conveyor; the supports having curved guide portions :32 adjacent the turns of the conveyor to direct the containers properlyat the inlet and discharge ends of the apparatus from the inlet chute H and onto discharge chute l9, respectively. In'sterilizing chamber 'L'contai-ners 9 aresu-pported on their sides on an apertured horizontally positioned fiat or planar support member 33 underneath the portion of the e nveyin 'r ach of the conveyor in the sterilizing chamber and which underlaps stationary support 3! at the inlet? end of the sterilizing chamber; and also underlapsa stationary container support member 34 in temperature holding chamber I2. Sup- "port member'sfi may be conveniently made of an aperturcd "metal plate having side flanges 3.5,

and is mounted for back and forth reciprocatable movement bymeans of side rollers 36 journalled o'n'fianges 35 and adapted to ride on rails 31 supported by brackets 33 on the side Walls of the .gagement between the containers and the supprising bracket 39 secured to the underside of support member 33 and to which is pivotally connected a pitman rod 4! in turn pivotally con nected to crank wheel 42 which is driven by any suitable drive mechanism 43. As the containers are conducted by the conveyor in one direction and on their sides along support member 33, it is seen thatas the support member is reciprocated, a rapid back and forth rolling motion is imparted to the containers by the frictional en- :port member, causing the containers and their contents to be thoroughly agitated. This enhances thorough penetration of heat through the containers imparted by steam which is supplied to the sterilizing chamber in a manner to be subsequently explained.

In intermediate temperature holding chamber 12., the agitating mechanism, although it may be employed, is not required because the sterilizing temperature is merely .held in this chamber. Conveyor tiico-nducts the containers with unidirectional rotation through the temperature holding chamber |2 along stationary container support member 34. In the cooling chamber wherein the containers and their contents are cooled, preferably by Water spraying, I preferably employ the described agitating mechanism therein to effect agitation of the containers and their contents, and thus enhance thorough cooling by the water spray. The construction of the agitating mechanism in such cooling chamber is the same as that in sterilizing chamber 1 and consequently the same general reference characters are applied to the main parts thereof.

Means is provided for efiecti-ng sterilization of the container contents in sterilizing chamber 1 as the containers are conducted therethrough. I utilize steam as the medium to heat the containers so as to sterilize their contents; and -I apply outside heat to the steam to bring it to a desired sterilizing temperature above 212 the steam being thus superheated at substantially atmospheric pressure as the entire inside of my apparatus will be at substantially atmospheric pressure by virtue of the valveless openings to the outside atmosphere. Any suitable means may be employed to superheat the steam at atmospheric pressure, but I preferably utilize the arrangement illustrated which enables recirculation of the steam.

With particular reference to Fig. 3, it Will be noted that sterilizing chamber I forms part of an endless passageway 44. This passageway comprises an upright portion'46 communicating with .the top of the sterilizing chamber by means of a steam discharge hood 4'! extending into the chamber and having a discharge end 48 above the portion of conveyor [6 in the sterilizing chamber. End .48 isprovided with a multiplicity of steam discharge apertures 49 and it is substantially coextensive with the portion of the conveyor in the chamber, so as to distribute the steam uniformly over the containers as they are conducted through the chamber. The upper end of passage portion 46 communicates with another upright passage portion 5|; and also forming part of endless passageway 44 is a bottom portion 52 communicating with the bottom of sterilizing chamber 1 and also with the bottom of passage portion 5 I. Preferably, the entire passageway 44 is lined with suitable moisture resistant'insulating material 5.0, such as corrosionresistant sheet metal backed with suitable insulation.

A fan 53 of any'suitable construction is provided in-passageway 44 to eifect circulation-of thesteam, introduced through a steam inlet pipe 54, Y through the passageway and through the sterilizing chamber I; a suitable valve 56 being provided in steam inlet pipe 54 to control .the quantity of steam flow. Preferably, the bottom of sterilizing chamber 1 is sloped toward passage portion 52 so that any steam condensate collecting-in'the sterilizing chamber may escape into passage portion 52 from which it may be drained, when theapparatus is shut down, through valve 57; From the precedingdt is seen that steam introduced-intoendless passageway 44 will be continuously circulated therethrough and through the sterilizing chamber, by fan 53, and that any steam escaping from the system can be made up the elimination of valves in theapparatus which were, heretofore, deemed necessary for obtaining a proper sterilizing temperature above 212 F. by maintaining the steam at superatmospheric pressure. In my apparatus and method, I provide any suitable outside heating means for superheating the steam to a sterilizing temperature above 212 Feat substantially atmospheric pressure. Such means may be electrical or any other type of heating means, but I preferably employ gas. For this purpose, a side of portion 46 of passageway 44 is provided with a relatively small furnace 6| having a gas burner 62 therein, and an opening 63 for inlet of air to enable combustion of,the gas flowing from burner 62.

Furnace. 6| is lined-with refractory insulatin material-64; and a plurality of fire tubes 65 communicating with the furnace, extend across passage portion 46 and communicate with a manifold chamber 66 at the opposite side of passage portion 46. Another group of fire tubes 61 above fire tubes 65 communicates with manifold chamber 66 and extends across both passage portions 4.6 and their outlet ends communicating with stack 68. By this arrangement, steam circulated in passageway 44 becomes heated to the desired sterilzing temperature by the hot gases of combustion flowing through the groups of fire tubes 65. and 61. The temperature to which the steam is superheated at atmospheric pressure, may be readily controlled by control of the flow of gas burned by 'burner 62; and if desired, such temperature may beautomatically controlled through any automatic thermostat control mechanism 69s'hown schematically in Fig. 3 and which may be connected to control the quantity of gas flow throughburner 62 by any "suitable automatic mechanism in a well known manner.

The conveyor is operated at such speed as to causethe contents in the containersto be heated to the proper sterilzing temperature as they are co nductedthrough the sterilizing chamber 1.. In

this connection, the sterilizing chamberl may. I long enough so that the. product will ,be in it i-for sufiicie nt length of time, depending upon. theparticular product and the rate of movement" be made of the conveyor, to become completely sterilized. However, to shorten the length of the sterilizing chamber, I preferably employ temperature holding chamber l 2 in conjunction therewith, but this chamber may be omitted if the sterilizing chamber is made long enough.

Such temperature holding chamber [2 is provided with a suitable heater H which may be in the form of a'steam radiator as shown, or a gas burner or anyother suitable heating means,

which is maintainedat the proper temperature for holding the temperature holding chamber at a sterilizing temperature so that'the product willv be maintained at such sterilizing temperature for a sufii'cient'len th of time depending upon the rate of speed of the product through the cham ber.

sprays emitted from the apertured water spray pipes13; and the cooling is enhanced by the agitation imparted to the containers and their contentsas they are conducted through the cooling chamber in the manner previously described.

Cooling may 'befurther enhanced, if so desired,

byfdrawing or forcing a current of air through the cooling chamber, by any suitable fan arrangement (not shown), such air current exerting a cooling effect by vaporization of water from the hot containers. Drain pan 1! is provided at the bottom of the cooling chamber to collect the sprayed water which is discharged through outlet 18.

From the preceding, it is seen that I have provided a comparatively simple apparatus )and method for efiicaciously sterilizing the product in sealed containers. and in which no valves are utilized at the inlet and discharge openings of the apparatus, thus simplifying the apparatus; steam being employed as the heating medium and the steam being superheated to a sterilizing temperature above 212 F. at atmospheric pressure. My improved agitating mechanism cooperates with the method of heating the containers and their contents because of the efficient agitation which is imparted to the containers-as they are conducted along their sides by the endless conveyor, while a simultaneous rapid back and forth rolling movement is imparted to the containers.

Although so-called tin can containers are sche tainers comprising a sterilizing chamber, an end-.

less passageway of which the chamber forms a part, .means for introducing steam -.into said passagewaypmeansifor efiecting circulation of said steamlinthe' passageway and through the chamerror applying heat to the containers to sterilize.

the product therein, means-for superheating the steam ,to ,.a,.st,e ri1izing temperature ,as it. is circiilated through the passageway means m Preferably, I employ in the temperature holding chamber a thermostat control l2 which tainers..compr1s1ng"'asterilizing chambe ha.

a witness inlet openingforf. introduction pfitheif containers into the 'ch, "mber whereby? thein'side o fe the e will be fat wsubstantially"atmos: p i p e sures cooling chamber in which theu can airlers ale subs quentl "cdoieda a which is for c riducting' -,the1containers;nieansicoop a,t.-..

'th 'portion ofthe'conveyorin'said'steriL iz ng c bertoimlja'rta back and forth rolling metr ltojsa id containers as they are conducte i product," while t e-containers "are conduc .10 tgvali ll ss communicati n j t i eriliz chamlo'erf means (including an enmess, onveyor,

byf'the {conveyor for iiagitating the containers and f? their contents, Ineansfor introducing steam into th'e'fsterilizing chamber. for applying heat the T containers i t'oIsterilize the product therein, and; means for superheating the steam toi alsteriliz ing temperature. at substantially. [atmospheric pressure V 1 h 3."Apparatus for sterilizing a product in cone tainersfcomprising" a sterilizing chamber having a .va1ve1ess,inlet opening one end for introduc tio of the containers into'the chamber whereby .insideof the chamberow ill beat substantially atmospheric pressure, a temperature holdingchamber in valv'gfless communication with the; opposite end i of said sterilizing chamber, Ta" cooling chamber in. valveless' communication at jv one end with said temperature holding chanibeiis. and: having a valveless diseharge. opening. opposite end f for dischargeof the conta' erg; means I including 7 an endless conveyor in said", chamber, for conducting the containers,lareeiprd-, l catablel container support member cooperating with the vportion of the conducting reaclifofjsaid endless conveyor in each of said sterilizing' and cooling chambers. to impart, a rapid back and forth;.rolli ng motion to said containers as they" are conducted byeth conveyorior agitatingthe containers and their contents, meansrfo r c0o1.-,

ing the ,containersinthe coolingchamber, means fqij heati ng the temperature holding chamber,v means for introducing steam into the sterilizing. chamher for applying heat to the containers to' sterilize the product therein, including ahood above the portion of the conveyor in the sterilizing chamber and having an apertured discharge en substantially coextensive with said conveyor pgr onto distribute the steam uniformly over sai cl containers, and means for superheating the st ea n to asterilizing temperature at substanmq p er c u e- 4, Apparatus for sterilizing aproduct in container'scomprising asterilizing chamber, an endless passageway of which the chamber forms a ans for introducing steam, into said pasa fan in said passageway for effecting tron .of, .said.steam in the passageway and containersto sterilize thejproduct therein, means including an endless conveyor for conducting the conta'nei s through the chamber, said passage- Qeludi l a steamdischarge hood adjacent said conveyor and having an apertured discharge,

end substantially coextensive with the portion of thejconveyor in said chamber to distribute the steam uniformly over said containers, and means fo r superheating the steam to a sterilizing temerate; i i c rc ate ehth pass eflY- fietmee wt t izin Pm Qt-ie thejchamber .for, applying heat to the throughlthefzone imparting to them a rapid' bak and'forth rolling motion to a'gitat'e'the containers and their contents and thereby enhance heat"? penetration, "and "superheating the steam-m "a"; steliz g temperaturei'at siihstantially atnr'os pherio pressure? :1

'SJjIn'th'eprQcessing of la product in containers, the method' oflagitatifigthe" containers andtheir contents which comp if tainers'dn theirjsides, "while. th ported moving said containers in one enerator rection with an "uninterrupted" motion with? unidirectional rotates; and smultaneously im parting tothe support 'a' bask s aman-ream catmg'jmt mn to roll "the containers back and form? r i '7," Tn productprocessing apparatus wherein the product is" ins-seaiea eomaini"mebhafiiin "6 5": agitating the product filled containerfto' agitate the pr oduct therein, 'e mprismg' a plate fiiition en agifigfana Suppertingthe 'product t me; container on itsfside, anlend e ss ccnveyor' having one oifits reaches positioned above "said plate, means continuously moving conveyor w ere; f by saidr'each is moved continuously in oneggen eral directio aid conveyorrea-ch 'havin g'acfoss a t g ei' rqcmc J fa on neri ne' mo'vingit on its sidein said one'generai direcfi e lwh le were nemas. -f" portedon saidplate and mechanismconneo d:

' om, vthe. j l t. aitin I mll ham ii d ut'tbrQu hfihejmitl i h e. a ean ijvn insaid chamber simultane usIfa gitatihg the" containers and the product therein as theyfare conducted through the; chamber, means tari nectedto said chamloerintrdducingsteani into h iba-mbeli in u-r eett he s ente si; ste ilize the, p fldl q heifiinz n 11' mechanism. associated with said steam in ducingfmea'ns applying" external heat tofthe steam ture above 212? Fllatsaid atmospheric pressure, 7 A 9. A method, of sterilizing aproduct in sealed. containers which comprises providing an enclosed, zone having unsealedinletrand outlet openings, whereby said zone is unsealdt'o the atmosphere" and the interior of said zone'will be at subst'am tially atmospheric pressure, continuously c'o'nduetin g a "oi" the product filled T containers "said zg eanufur whilesaidproductj ted triraiigflsaidzo e" n C lie 9 v, to apply heat to the containers and sterilize the product therein, and applying external heat to said steam introduced into said zone to superheat the steam to a sterilizing temperature abov 212 F. at said atmospheric pressure.

WILLIAM McK. MARTIN.

REFERENCES CITED The following references are of reeord in the" file of this patent:

UNITED STATES PATENTS Number Name Date 274,595 Hayden Mar. 27, 1883 876,534 Farnum et a1; Jan. 14, 1908 Number Number Denmark Jan. 11, 1937 

1. APPARATUS FOR STERILIZSING A PRODUCT IN CONTAINERS COMPRISING A STERILIZING CHAMBER, AN END LESS PASSAGEWAY OF WHICH THE CHAMBER FORMS A PART, MEANS FOR INTRODUCING STEAM INTO SAID PASSAGEWAY, MEANS FOR EFFECTING CIRCULATION OF SAID STEAM IN THE PASSAGEWAY AND THROUGH THE CHAMBER FOR APPLYING HEAT TO THE CONTAINERS TO STERILIZE THE PRODUCT THEREIN, MEANS FOR SUPERHEATING THE STEAM TO A STERILIZING TEMPERATURE AS IT IS CIRCULATED THROUGH THE PASSAGEWAY, MEANS FOR CONDUCTING THE CONTAINERS THROUGH THE CHAMBER, AND 